Search

Quantum tomography provides the full reconstruction of the density matrix of a state. We use it to study the Higgs boson decay into weak gauge bosons. Anomalous couplings beyond the Standard Model can be constrained by means of observables easily defined in terms of the polarization density matrix. We describe a strategy based on three observables that together provide the most stringent limits. Two of these observables are linked to the entanglement between the polarizations of the two gauge bosons, the other is based on CP-odd combinations of one momentum and two polarizations. We find for the Z channel that this strategy offers, already with the available LHC data, limits competitive with the best available bounds. We argue that the inclusion of these observables in routine experimental analyses can lead to more stringent global fit limits. [ABSTRACT FROM AUTHOR]

We discuss how two birds-the little hierarchy problem of low-scale type-I seesaw models and the search for a viable dark matter candidate-are (proverbially) killed by one stone: a new inert scalar state. [ABSTRACT FROM AUTHOR]

We discuss a minimal extension to the standard model in which two singlet scalar states that only interacts with the Higgs boson are added. Their masses and interaction strengths are fixed by the two requirements of canceling the one-loop quadratic corrections to the Higgs boson mass and providing a viable dark matter candidate. Direct detection of the lightest of these new states in nuclear scattering experiments is possible with a cross section within reach of future experiments. [ABSTRACT FROM AUTHOR]

Whenever fields are allowed to propagate in different portions of space-time, the four-dimensional theory exhibits an effective violation of the principle of equivalence. We discuss the conditions under which such an effect is relevant for neutrino physics. In the simplest case of compactification on a flat manifold, the effect of gravity is many orders of magnitude too weak and plays no role for solar neutrino oscillations. Instead, it could be important in the study of ultra high energy neutrinos in cosmic rays. Gravity could also be relevant for lower energy neutrino processes involving bulk sterile states, if the mechanism of compactification is more subtle than that on torii. [ABSTRACT FROM AUTHOR]